I had an old Gun Digest with an article showing that sort of thing.
Including a correct replica Walker shop made at a cost of $300 in the early 1950s.
Add a dummy cock and frizzen to that Trapdoor to simulate a flintlock.
Early tv Annie Oakley carried a Police Positive Special with dummy side rod ejector, plastic stag, and nickel plate.
Rock Hudson carried a Colt cartridge conversion in Seminole. Still out of period so why did they bother? And where did they get them?
Big Jake's son carried a prop Bergmann, faked up from a P38.